The present invention relates to a multi-layer printed-wiring board and a process for producing it, and transferring original plates used in producing the multi-layer printed-wiring board and a process for producing them, and particularly to a multi-layer printed-wiring board having a highly precise pattern, a process for producing such a multi-layer printed-wiring board at low cost, and transferring original plates with which the above multi-layer printed-wiring board can be advantageously produced from the industrial viewpoint, and a process for producing them.
Remarkable development of the semiconductor technology has made rapid progress in miniaturizing semiconductor packages, using a configuration of as many pins as possible, realizing fine pitches, and minimizing the dimensions of electronic parts, thereby rushing into a so-called high-density packaging era. With the progress, the printed-wiring boards are also changing from single-side wiring to double-side wiring, and further to multi-layer wiring and thin-film structure.
Presently, the subtractive process and the additive process are mainly used to form copper patterns on the printed-wiring boards.
The subtractive process is a process consisting of forming holes in a copper-clad laminate, thereafter depositing a copper plating layer inside the holes and on the surface of the laminate, and then performing photo-etching to form patterns. This subtractive process is technically highly completed and low in cost, but it is difficult to form fine patterns because of restriction resulting from the thickness of a copper foil, for example.
On the other hand, the additive process is such a process that a resist layer is formed on portions except for circuit-pattern-forming portions on a laminate containing a catalyst for electroless plating and that circuit patterns are formed on the exposed portions on the laminate by electroless copper plating or the like. The additive process does permit fine patterns to be formed, but has drawbacks in terms of cost and reliability.
Used for forming multi-layer boards is a method for laminating under pressure a single-sided or double-sided printed-wiring board produced by either of the above methods etc. together with a pre-preg in a semi-curing condition, in which an epoxy resin etc. is impregnated in glass cloth. In this case, the pre-preg roles as an adhesive for layers, and connection between the layers is made by forming through holes and effecting electroless plating inside thereof.
Further, the progress of the high-density packaging demands to decrease the thickness and weight of multi-layer boards and also to raise wiring capacity per unit area, which results in producing ideas on the decrease of the thickness of board per layer, the method for connection between layers, the method for mounting parts, etc.
However, the production of multi-layer board using the double-side printed-wiring board produced by the above subtractive process had a limit of increasing the density in terms of the precision of drilling for forming holes in the double-side printed-wiring board and the limit of scale down, and was difficult to decrease the manufacturing cost in addition.
On the other hand, there is a recently developed multi-layer wiring board that is produced by laminating electrically conductive pattern layers and electrically insulating layers successively on a substrate, which meets the above-described demand. Since this multi-layer wiring board is produced by alternately performing photo-etching of a copper plating layer and patterning of a photosensitive resin, this process permits highly precise wiring and connection between layers at arbitrary position.
However, because in this method the copper plating and photo-etching were performed alternately plural times, the procedures were complicated; and because this method was a series process in which the layers were laminated one by one on the substrate, it was difficult to recover a product once trouble occurred in an intermediate step, which was a hinderance to the decrease in the production cost.
Furthermore, because in the conventional multi-layer wiring boards, connection between layers was effected by forming via holes, complicated photolithography steps were required, which was another obstacle against the decrease in the production cost.
The present invention has been accomplished taking the above points into account, and an object of the present invention is to provide a multi-layer printed-wiring board having a highly precise pattern, a process in which such a multi-layer printed-wiring board can be produced by a transfer-lamination-on-substrate method without including the photolithography step, transferring original plates with which the above multi-layer printed-wiring board can be advantageously produced from the industrial viewpoint, and a process for producing them.
A first feature of the present invention is a multi-layer printed-wiring board comprising a substrate for multi-layer printed-wiring board and a plurality of wiring pattern layers having sequentially been transferred onto the substrate, wherein each wiring pattern layer has an electrically conductive layer and an electrically insulating resin layer formed below the electrically conductive layer, and said insulating resin layer is fixed to the substrate or to a lower wiring pattern layer.
A second feature of the present invention is a multi-layer printed-wiring board comprising a substrate for multi-layer printed-wiring board and a plurality of wiring pattern layers having sequentially been transferred onto the substrate, wherein each wiring pattern layer has an electrically conductive layer and an electrically insulating resin layer formed below the electrically conductive layer; said insulating resin layer is fixed to said substrate or a lower wiring pattern layer; and an additional electrically insulating layer is interposed in an overlapping portion between the wiring pattern layers.
A third feature of the present invention is a multi-layer printed-wiring board comprising a substrate for multi-layer printed-wiring board and a plurality of wiring pattern layers having sequentially been transferred onto the substrate, wherein each wiring pattern layer has an electrically conductive layer and an adhesive layer formed below the electrically conductive layer, and an insulating resin layer is formed between upper and lower wiring pattern layers in a portion where the wiring pattern layers intersect or overlap in multi-layer structure with each other.
A fourth feature of the present invention is a multi-layer printed-wiring board comprising a substrate for multi-layer printed-wiring board and a plurality of wiring pattern layers having sequentially been transferred onto the substrate, wherein each wiring pattern layer has an electrically conductive layer, and an electrically insulating resin layer is formed between upper and lower wiring pattern layers in a portion where the wiring pattern layers intersect or overlap in multi-layer structure with each other.
A fifth feature of the present invention is a printed-wiring board comprising a substrate for printed-wiring board and a wiring pattern layer formed on the substrate, wherein a part of said wiring pattern layer is constituted by arranging a plurality of lines each having a small linewidth in parallel.
A sixth feature of the present invention is a process for producing a multi-layer printed-wiring board, comprising:
a step of forming on electrically conductive substrates respective wiring pattern layers, each having an electrically conductive layer and a sticky or adhesive, electrically insulating resin layer laid on said conductive layer, thereby preparing a plurality of transferring original plates; and
a step of pressing said transferring original plate onto a one-side surface of the substrate for multi-layer printed-wiring board and releasing said electrically conductive substrate, thereby transferring said wiring pattern layer to said substrate;
wherein the transferring step of said wiring pattern layer is sequentially repeated with the plurality of transferring original plates, thereby laying the plurality of said wiring pattern layers in lamination on said substrate.
A seventh feature of the present invention is a process for producing a multi-layer printed-wiring board, comprising:
a step of forming on electrically conductive substrates respective wiring pattern layers, each having an electrically conductive layer and a sticky or adhesive, electrically insulating resin layer laid on said conductive layer, thereby preparing a plurality of transferring original plates; and
a step of pressing said transferring original plate onto a one-side surface of the substrate for multi-layer printed-wiring board and releasing said electrically conductive substrate, thereby transferring said wiring pattern layer to said substrate;
wherein before laying the wiring pattern layers one over another, an additional insulating layer is preliminarily formed on an overlapping-intended portion of wiring pattern layers in a lower wiring pattern layer, and said step of transferring said wiring pattern layer is sequentially repeated with the plurality of transferring original plates, thereby laying the plurality of said wiring pattern layers in lamination on said substrate.
An eighth feature of the present invention is a process for producing a multi-layer printed-wiring board, comprising:
a step of forming on electrically conductive substrates respective wiring pattern layers, each having an electrically conductive layer and an adhesive layer laid on said conductive layer, thereby preparing a plurality of transferring original plates;
a step of pressing a lower transferring original plate onto a one-side surface of the substrate for multi-layer printed-wiring board and releasing said electrically conductive substrate, thereby transferring said wiring pattern layer to said substrate;
a step of forming an insulating photosensitive resin layer so as to cover said lower wiring pattern layer, pressing an upper transferring original plate onto said insulating photosensitive resin layer, and releasing said electrically conductive substrate, thereby transferring the upper wiring pattern layer to said resin layer; and
a step of performing exposure and development of said insulating photosensitive resin layer with the upper wiring pattern layer transferred as a mask.
A ninth feature of the present invention is a process for producing a multi-layer printed-wiring board, comprising:
a step of forming on electrically conductive substrates respective wiring pattern layers, each having an electrically conductive layer, thereby preparing a plurality of transferring original plates;
a step of forming an adhesive insulating photosensitive resin layer on a one-side surface of the substrate for multi-layer printed-wiring board, pressing said transferring original plate onto said adhesive insulating photosensitive resin layer, and releasing said electrically conductive substrate, thereby transferring said wiring pattern layer to said substrate; and
a step of performing exposure and development of said adhesive insulating photosensitive resin layer with said wiring pattern layer transferred as a mask,
wherein the step of transferring the wiring pattern layer and the exposure and development step of the adhesive insulating photosensitive resin layer are sequentially repeated, thereby laying a plurality of said wiring pattern layers in lamination on said substrate for multi-layer printed-wiring board.
A tenth feature of the present invention is a process for producing a multi-layer printed-wiring board, comprising:
a step of forming on electrically conductive substrates respective wiring pattern layers, each having an electrically conductive layer and an adhesive layer laid on said conductive layer, thereby preparing a plurality of transferring original plates;
a step of pressing a lower transferring original plate onto a one-side surface of the substrate for multi-layer printed-wiring board and releasing said electrically conductive substrate, thereby transferring said wiring pattern layer to said substrate; and
a step of forming an insulating photosensitive resin layer so as to cover the wiring pattern layer on said substrate, pressing an upper transferring original plate onto said insulating photosensitive resin layer, and releasing said electrically conductive substrate, thereby transferring the upper wiring pattern layer to said resin layer;
which further comprises a step of sequentially repeating the step of transferring the upper wiring pattern layer to lay a multiplicity of wiring pattern layers in lamination on the substrate for multi-layer printed-wiring board, and thereafter performing exposure and development of said insulating photosensitive resin layer with said wiring pattern layers as a mask.
An eleventh feature of the present invention is a process for producing a multi-layer printed-wiring board, comprising:
a step of forming on electrically conductive substrates respective wiring pattern layers, each having an electrically conductive layer, thereby preparing a plurality of transferring original plates; and
a step of forming an adhesive insulating photosensitive resin layer onto a one-side surface of the substrate for multi-layer printed-wiring board, pressing said transferring original plate onto said adhesive insulating photosensitive resin layer, and releasing said electrically conductive substrate, thereby transferring said wiring pattern layer to said substrate;
which further comprises a step of sequentially repeating the step of transferring the upper wiring pattern layer to lay a multiplicity of wiring pattern layers in lamination on the substrate for multi-layer printed-wiring board, and thereafter performing exposure and development of said insulating photosensitive resin layer with said wiring pattern layers as a mask.
A twelfth feature of the present invention is a process for producing a printed-wiring board, comprising:
a step of forming a current-carrying film on a one-side surface of a substrate for printed-wiring board;
a step of forming a patterning layer having a predetermined wiring pattern on the current-carrying film and exposing said current-carrying film with a wiring pattern in which a plurality of lines each having a small linewidth are arranged in parallel;
a step of forming an electrically conductive layer on said current-carrying film exposed by electro-deposition; and
a step of removing said patterning layer and further removing the current-carrying film exposed by etching.
A thirteenth feature of the present invention is a process for producing a printed-wiring board, comprising:
a step of forming a transferring original plate provided with a wiring pattern layer comprised of an electrically conductive layer and an adhesive layer by forming the electrically conductive layer on an electrically conductive substrate by electro-deposition with a wiring pattern in which a plurality of lines each having a small linewidth are arranged in parallel, and then forming the adhesive layer on the conductive layer by electro-deposition; and
a step of pressing said transferring original plate onto a one-side surface of a substrate for printed-wiring board and releasing said electrically conductive substrate, thereby transferring said wiring pattern layer to said substrate.
A fourteenth feature of the present invention is a transferring original plate comprising an electrically conductive substrate at least a surface of which is electrically conductive, an electrically insulating masking layer of a desired pattern formed on the electrically conductive substrate, and an electrically conductive layer formed on said electrically conductive substrate and between regions of the insulating masking layer.
A fifteenth feature of the present invention is a transferring original plate comprising an electrically conductive substrate at least a surface of which is electrically conductive, an electrically insulating masking layer which is formed on the electrically conductive substrate so as to expose the electrically conductive surface of said conductive substrate in such a desired wiring pattern as a set of lines each having a small linewidth, and an electrically conductive layer formed by electro-deposition on said electrically conductive substrate and between regions of the insulating masking layer.
A sixteenth feature of the present invention is a process for producing a transferring original plate, comprising:
a step of forming an insulating masking layer in a desired pattern on an electrically conductive substrate at least a surface of which is electrically conductive; and
a step of forming an electrically conductive layer on an exposed portion of the surface of said electrically conductive substrate by electro-deposition.